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SQL Server Compact 3.5 introduces the following features for software developers.

Installation and Database File Upgrade

Support for side-by-side installation together with the previous version (3.1) on desktop computers. If you try to open database files created by using earlier versions, SQL Server Compact 3.5 will give you a message that the file cannot be opened. To open it, the database file first must be upgraded by using the Upgrade to SQL Server Compact 3.5 Database dialog box in Visual Studio 2008. To access the Upgrade to SQL Server Compact 3.5 Database dialog box, click Data, click Add New Data Source, and then click Add Connection. When you try to open an earlier version of the database file, you receive a message. By selecting OK, the Upgrade to SQL Server Compact 3.5 Database dialog box appears. The file name extension of SQL Server Compact 3.5 is *.sdf, which is the same as that of the earlier versions (SQL Server Compact Edition, v. 3.1, and SQL Server 2005 Mobile Edition, v. 3.0). After a database file is upgraded to SQL Server Compact 3.5, you will no longer be able to open the database file by using earlier versions of SQL Server Compact. Database files created by the earlier versions of SQL Server Compact 3.5 can be programmatically upgraded by using the SqlCeEngine.Upgrade API. Refer to the documentation for more information.

To support older operating systems, with older encryption algorithms, and newer, more secure encryption, SQL Server Compact 3.5 supports backward-compatible encryption modes. The encryption modes available in the Upgrade to SQL Server Compact 3.5 Database dialog box are as described in the following list.

Platform Default: When you create or upgrade SQL Server Compact databases, Encryption mode will select the default encryption for the operating system. By creating a database on one of the newer platforms shown here, older platforms (such as Windows CE 4.2 or Windows Mobile 2003) will be unable to open encrypted SQL Server Compact files. The older platforms do not support the newer encryption algorithms.

Windows CE 5.0

Windows CE 6.0

Windows Mobile 5.0

Windows Mobile 6.0

Windows XP

Windows Server 2003

Windows Vista

For example, if the database is created on Windows XP, it will select encryption for Windows XP. The encrypted database created on Windows XP with the Platform Default option cannot be opened on Windows CE 4.2 or Windows Mobile 2003 for Pocket PC.

Engine Default: By default, the encryption mode for the SQL Server Compact 3.5 database file will not work on Windows CE 4.2 or Windows Mobile 2003 Software for Pocket PC. This encryption mode will work on all newer SQL Server Compact 3.5 supported platforms.

Windows CE 5.0

Windows CE 6.0

Windows Mobile 5.0

Windows Mobile 6.0

Windows XP

Windows Server 2003

Windows Vista

PPC2003 Compatibility: While less secure, this option can be used to support older and newer operating systems including:

SQL Server Compact 3.5 now includes a new developer oriented, componentized synchronization model by using Synchronization Services for ADO.NET, available for desktop computers only.

Server Tools for configuring Merge Replication and RDA by using SQL Server Compact 3.5 can be downloaded from the Microsoft Download Center. Note that SQL Server Compact 3.5 Server Tools cannot be installed side-by-side with earlier versions of Server Tools on the computer that is acting as the IIS server. SQL Server Compact 3.5 Server Tools can replicate data between SQL Server Compact 3.5 and SQL Server 2005 and later versions. The Server tools can also support synchronization between SQL Server 2005 and SQL Server Compact 3.1. SQL Server Compact 3.5 Server Tools also supports data replication between SQL Server 2005 Compact Edition or SQL Server 2005 Mobile Edition and SQL Server 2005 and later versions.

Programmability

Supports local TransactionScope on desktop computers.

SQL Server Compact 3.5 supports LINQ to SQL. LINQ to SQL is a component of the LINQ project. It provides a run-time infrastructure for managing relational data as objects, without giving up the ability to query. It translates language-integrated queries into Transact-SQL for execution by SQL Server Compact 3.5, and then translates the tabular results back into the objects as defined by the application developer. There is no designer support for SQL Server Compact 3.5 in LINQ to SQL. The SqlMetal.exe utility must be used for SQL Server Compact 3.5. For more information, see the documentation.